Broadcast radio frequency signal strength degrades or attenuates as it crosses a physical distance. The degradation of an unimpeded radio signal is mathematically predictable, based on the radio propagation environment. Increased distance and decreased signal strength are closely related. When an unobstructed radio signal of known originating strength is received and measured by a receiving station, the approximate distance from the transmitting station can be assessed. Objects which intervene between the transmitting and receiving stations disturb the mathematics of the signal decay function. Determining distance from a transmitter based on measuring signal strength inside of buildings and other crowded or cluttered places is problematic as randomly disposed obstructions may diminish signal strength in unpredictable ways.